This image shows a part of the western flank of Ascraeus Mons. Ascraeus Mons is one of the giant volcanoes of the Tharsis volcanic region of Mars.

It is a shield volcano, so named because of the gently-sloped round shape. Terrestrial examples, like Mauna Loa and Kilauea on Hawaii, are formed mostly by repeated eruptions of fluid (basaltic) lava. Martian volcanoes can attain much larger sizes partiallly because Mars lacks plate tectonics, allowing eruptions to persist at the same site for a long time.

In this HiRISE image, the surface is covered by a mantle of dusty material which obscured the underlying surface. This has been sculpted into regular textures, probably by aeolian (wind) erosion. It appears that there are multiple layers, as the southeast portion of the image shows textured knobs standing above a similarly patterned surface. The origin of the dusty mantle is unclear. It could be wind-blown dust, but it is also possible that some of it is volcanic ash erupted from Ascraeus Mons.
Written by: Colin Dundas

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible: Image: NASA/JPL/University of Arizona

For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.